The only people who call them frats are the people who think frat boys wear Abercrombie and Fitch and pooka shell necklaces. Nobody who is a part of greek life (in the SEC/Big 12 south anyway, I don't know about other places) would call their fraternity a frat.

lol it just doesn't make sense to me. i wouldn't call my country a ****... but i would call the united states of america the USA.. because it's much shorter and easier to say. but i guess there are some negative connotations to the word "frat" that people associated with "frat"ernities would prefer to avoid